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Heart Health

Updated 16 October 2015

Arrhythmia

An arrhythmia is any deviation from the normal rhythm of the heart. Arrhythmias are important as they cause unpleasant symptoms, which may progress to serious complications.

Summary

  • An arrhythmia is any deviation from the normal rhythm of the heart. The normal heart rhythm is called sinus rhythm.
  • Arrhythmias are important as they cause unpleasant symptoms, which may progress to serious complications. Some may even be life-threatening.
  • Arrhythmias may result from most heart diseases and can occur without apparent cause.
  • The details given by the patient, plus examining the pulse and listening to the heart sounds, will make a clinical diagnosis.
  • Arrhythmias are best treated by referral to a specialist cardiologist. Any identified underlying disorder contributing to the arrhythmia must be treated in its own right.
  • With appropriate treatment, most arrhythmias will revert to normal sinus rhythm.

What causes it?

This SA node controls the rate and rhythm of the whole heart. It is under the control of the autonomic part of the nervous system, which is not under conscious control but which is responsible for the control of bodily functions such as the beating of the heart, intestinal movements, sweating, the production of saliva and other similar functions.

  • Ectopic beats, also called extrasystoles. These are heartbeats which are due to an impulse generated somewhere else in the heart outside the SA node. If they originate in the atria, they are called supraventricular. If they arise in the ventricles, they are called ventricular. They may be produced by any heart disease, caffeine or from smoking. They are common in normal people who may be unaware of them, or may feel that the heart has "missed a beat".
  • Bradycardia, in which the heart rate is slower than normal, and tachycardia, in which the heart rate is faster than normal.
  • Fibrillation is a rapid and chaotic beating of the many individual muscle fibres of the heart. This stops the heart from maintaining its effective and synchronous contraction, which is vital to its function. The affected part of the heart ceases to pump blood.
  • Heart block, which is often associated with slow heart rates. This is a condition in which conduction of the electrical impulses generated by the SA node is impaired, causing the pumping action of the heart to slow down.

  • underlying heart disease, e.g. coronary artery disease or valve dysfunction
  • smoking
  • stimulants - either exogenous, e.g. caffeine, or endogenous, e.g. thyroid hormone
  • advancing age
  • obesity
  • certain medications, e.g. theophylline

Symptoms and signs

  • palpitations, which is the term used for a conscious perception of an abnormal heart rhythm
  • breathlessness
  • chest pain
  • dizziness
  • fainting
  • worsening of angina or heart failure
  • confusion
  • extreme fatigue

Who is at risk?

How is it diagnosed?

How is it treated?

What is the outcome

Prevention

When to see a doctor

 

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